Remote control hydraulic apparatus



May 25, 1948. H. E. PAGE 2,442,058

I 7 REMOTE CONTROL HYDRAULIC APPARATUS 1119a Dec. 26, 1 945 4Sheets-Sheet 1 IMWTEMII Ma May 25, 1948. H. E. PAGE REMOTE CONTROLHYDRAULIC APPARATUS Filed Dec. 26, 1945 4 Sheets-Sheet 2 m WH Rm :2 3 32L Jnv 15117101 Jianbart E.

May 25, 1948. H. E. PAGE REMOTE common HYDRAULIC APPARATUS Filed Dec.26, 1945 4 Shuts-Sheet 5 Patented May 25, 1948 REMOTE CONTROL HYDRAULICAPPARATUS Herbert E. Page, Dayton, Ohio Application December 26, 1945,Serial No. 637,278

' Claims.

My present invention relates to a remote control hydraulic apparatus,and more particularly to an apparatus for delivering hydraulic fluidwith a pressure and volume output which will vary in accordance withpredetermined load conditions.

An object of the invention is to make an improved and simplified remotecontrol hydraulic apparatus.

Another object is to make a hydraulic apparatus having an initial highcapacity output and a secondary lower capacity higher pressure output.

A further object is to make a hydraulic apparatus havin adjustablecontrols for increasing automatically the hydraulic pressure appliedupon a predetermined increase in the load.

A still further object is to make a plural actuating hydraulic apparatusadapted for an initial high volume, low pressure delivery under lightload, and changing automatically to a predetermined high pressure, lowvolume delivery upon the imposition of a predetermined load.

In order to attain these objects, and others which will be apparent froma perusal of the fol lowing description and the accompanying drawings, Iprovide in accordance with one feature of the invention an apparatushaving a plurality of cylinders of selected sizes, which are disposed atdifferent distances from a fulcrum. Pistons are mounted to operate inthe cylinders, through lever arms which may have a common fulcrum, todeliver different volumes of fluid at predetermined pressures in each.By means of simple controls the volume and pressure output of liquid bythe device may be varied as required to meet predetermined orencountered load conditions.

These and other features of the invention will be apparent from thefollowing description and the accompanying drawings, in which:

Figs. 1, 2 and 3 are respectively plan, side and end elevations of ahydraulic apparatus embodying the present invention;

Fig. 4 is a longitudinal vertical section taken on the line 4-4 of Fig.1;

Fig. 5 is a transverse vertical section taken on the offset line 55 ofFig. 4;

. Fig. 6 is a fragmentary transverse horizontal section taken on theline 6-45 of Fig. 5;

Fig. '7 is a vertical longitudinal sectional view through a blockincorporating the principal actuating parts of the apparatus taken onthe line 11 of Fig. 5; I

Fig. 8 is a similar view taken on the line 8-8 of Fig. 5; and

Fig. 9 is a horizontal transverse sectional view 2 through the sameblock taken on the line 99 of Fig. 5.

Referring to the drawings in detail, which illustrate a preferredembodiment of my invention, a casing i 0 of sheet metal or othersuitable material has a cylinder block H mounted within an end thereof.A liquid reservoir or storage cylinder l2 has one end thereof sealed'inan annular recess i3 in the block H. The other end of the reservoir issealed in a recess H in an end plate l5. A bolt ii having a sealinggasket is under the head thereof, passes through the end plate and isscrewed into a threaded opening in the block to draw the reservoircylinder parts together into liquid-tight sealed relation. A secondliquid reservoir IQ is mounted above the reservoir i2 and feeds liquidby gravity into the lower reservoir through a passage 20 interconnectingthe two reservoirs. A filler pipe 2| extends upwardly from the upperreservoir [9 to a point just below the level of the casing l0, and afiller cap 22 is secured in an opening in the casing over the fillerpipe M.

A pair of bearing supports 24 and 25 project upwardly from the forwardor discharge end of the block I i and in them a fulcrum shaft 26 ismounted for pivotal movement. An end portion 21 of the shaft 26 projectsoutwardly through an opening in a side of the casing It. An operatinghandle lever 2a is keyed to the projecting end portion 21 of the shaft26, and a piston operating lever 29 is keyed to the shaft 26 between thebearing supports 24 and 25.

. A pivot pin 32 is mounted in an opening drilled transversely throughthe piston operating lever 29 to have a press fit in the opening withboth ends of the pin projecting out from the sides of the lever. A pairof piston connecting links 30 and 3! are mounted with their upper endspivoted one on each of the projecting ends of the pivot pin 32. Thelower end of each of the piston connecting links 30 and 3! is divided,as shown in Fig. 5, and is connected pivotally to an upright projection33 on the upper end of each of a pair of pistons 34 and 35,respectively.

The piston 35 is illustrated as being larger in diameter than the piston34, it being apparent, however, that the diameters of the pistons may bevaried at will, and should be predetermined prior to manufacture so asto produce the pressures desired in the operation of the apparatus.

The pistons 34 and35 are mounted in cylinders 31 and 38 machined in theblock II. The walls of all the cylinders and pistons are finished inaccordance with good current practice, such as it to seal the passage.

by guiding, lapping, honing, or otherwise to produce a desired degree ofsmoothness and regularity.- Each cylinder has an annular ring groove 39in which is mounted a sealing ring 40 preferably or resilientv syntheticmaterial.

A third piston connecting link 4| is pivoted in a notch 42 in the outerend of the piston operating lever 29, the lower end or the link 4! beingconnected to a third piston 43. This third piston is generally similarto the other two, but is considerably longer and, as here illustrated,larger in diameter than either of the other two pistons, The piston 43is mounted in a cylinder 44 machined in the block I I similarly to theother two cylinders 81 and 38. The piston 43 also is provided with asealing ring '45 mounted in an annular groove therein.

Fluid passages are provided in the block from the reservoir l2 to thecylinders, the flow of fluid therethrough being controlled by valves andother mechanisms in the following manner:

A main inlet passage 41 opens into a lower portion of the lowerreservoir i2 and extends for: wardly to the plane of the lower portionof the ofiset sectional plane of Fig. 5, as indicated by the line 5-5 ofFig. 2. At this plane the passage opens into a laterally drilled passage48, the exposed end 49 of which is plugged. From this lateral passage 48two passages 50 and El extend upwardly, in rear of the high pressurecyl-v inders 31 and 38 respectively. Since both of these upwardlyextending passages are similarly constructed, only the right hand one 50as shown in Fig. 5 will be described in detail. This passage also isshown sectionally in Figs. 4 and 7,

The upper portion of each of the passages 5.0

is enlarged as at 52 and is further enlarged as at 53. A seat for a ballcheck valve is provided at each of these two enlargements of thepassages, and ball check valves 54 and 55 are mountedon the seats thusprovided. The enlarged upper end 53 of each passage is threaded, asshown in Fig. 7, and a plug 51 is screwed into Horizontal passages 58and 59 connect the first enlarged portions 52 of the passages 50 and 5|into the lower ends of the cylinders 31 and 38, respectively. Theforward ends of both of the horizontal passages 58 and 59 are plugged asat 60, see Fig. 7.

A cylindrical cam chamber BI is drilled transversely of the block H withits axis passing through the axes of the vertical passages 50 and A cam62 is inserted in the cam chamber 61, and has enlarged cylindrical endportions 83 and 64 thereof journalled in the cam chamber outwardlybeyond the vertical passages 50 and 5|. A sealing ring 65 is mounted ina groove near the outer end of the cam 62, and a snap retaining ring 6'!is inserted in an annular groove in the wall of the cam chamber tooverlie the outer end of the cam to secure it in position.

A cam operating handle 68 is mounted on a projecting stem portion 59 ofthe cam, and is secured thereto as by a pin iii. A spring pressed ball Hinserted in a recess 12 of reduced diameter in the base of the camchamber 6| exerts a resilient outward positioning force on the cam tohold it against the snap retaining ring 61.

A pair of cam lobes .13 and 14 are provided on the cam 62, one lobebeing positioned in alignment with each 01. the passages 50 and BI,respectively. The cam lobes .are of a height to provide suiilcientclearance inwardly from the wall of the cam chamber to permit a freeflow of liquid upwardly through the passages 58 and 4 6| at all times. Apin 15 of aslze and shape to permit hydraulic liquid to flow betweenitand the wall 01 the passage in which it is. mounted, is inserted in eachor the passages 50 and-ll. These pins are of a length normally to permitthe lower ball checks 54 to seat, but to raise the balls l of! theirseats when the pins 75 are raised by their respective cam lobes. and 14are arranged in partially overlapping and partially angularly offsetrelation, as shown in Fig. 1. In this manner either onepin or the otheror both may be raised by rotating the cam to bring the desired'cam lobeor lobes into operating position. By turning the cam to move both camlobes out of contact with both plus, it is apparent that both of thelower ball checks will be free to seat.

A lateral passage 71 shown in Figs. 4, 7, 8 and 9 connects the enlargedupper portions 53 or the 7 vertical passages 50 and ill to each other.This lateral connecting passage 11 in turn opens into the main fluiddischarge passage 18 opening out of the forward end of the block II. Afitting 19 may be threaded into the forward end of this passage toconnect the apparatus to a mechanism (not shown) to be supplied with thehydraulic fluid.

The above-described passages and associated parts comprise essentiallythe fluid intake, compression, control and discharge of the highpressure, low volume, side of the hydraulic apparatus embodying thepresent invention.

Referring now to the passages associated with the low pressure, hi hvolume cylinder 44 and its piston 43, a cylindrical valve chamber 80 'isdrilled upwardly from the bottom of the block I i, as shown in Figs. 4.7 and 9. This valve chamber 80 has an enlarged threaded lower endportion 8|, From the upper end of the valve chamber 80, a passage 82 ofreduced diameter opens upward, and at the upper end of this reducedpassage the passage is enlarged as at 83 to provide a valve seat for aninlet ball check valve 84.

A seat for a second, or outlet ball check valve 81 is formed between theupper end of the first enlarged passage 83 and a further enlargedpassage 85. The upper end of the passage 85 is plugged as at 88. r

A lateral passage 16 (see Figs, 7, 8 and 9) opens into the firstenlarged passage 83, between the upper and lower ball checks, and thislateral passage also opens into a vertical passage 86 which in turnopens into the main intake passage 41 from the reservoir l2.

A valve piston 89 is mounted slidably in the valve chamber 88, and ahydraulic sealing ring .mounted in a groove in the piston 89. A stem 8|projects upwardly from the valve piston 88 and is surrounded by abiasing coil compression spring 92 which is held in compression betweenthe upper end of the-valve chamber and the top of the valve piston 89,The upper portion 98 of the stem Si is further reduced in diameter andis shaped to permit free flow of hydraulic liquid between it and thewall 01' the reduced passage 82 above the valve chamber in which it isinserted. The length of this reduced stem portion 93 is such as to raisethe lower or inlet ball check 84 off its seat upon a predeterminedupward movement of the valve piston 89, and to permit the ball to reseatupon a predetermined return movement downward of the piston.

An axial opening 94 is drilled in the lower end of thepiston 89 toreceive a stem 95 which ex= The cam lobes I3 tends upwardly from acombined sealing and valve pressure adjusting plug 91. A coil spring 98surrounds the plug stem 95 and is heldin compression between the bottomof the piston 89 and the top of the plug 91. The plug 91 is threadedinto the enlarged lower end 8i of the valve chamber 80. The plug 91maybe adjusted axially by screwing it in or out as required to vary theforce opposing the biasing action of the coil spring 92. A hydraulicsealing ring 98 is mounted in a groove in the plug 91.

From the first enlarged passage 83 between the ball checks 84 and 81 apassage I opens into the lower end of. the large cylinder 44. A lowpressure discharge passage IOI connects the upper enlarged passage 85above the upper ball 81 to [the transverse passage 11 which in turnopens into the main hydraulic discharge passage 10. v

In order to connect the main discharge passage 18 with the valve chamber00 below the valve piston 89, a vertical passage I02 vextends downwardlyfrom the main discharge passage 18 to a lateral passage 96., The passage96 opens into a horizontal passage I03 which in turn opens into thevalve chamber 80. See Figs. 4, 7, 8 and 9.

To permit the release of pressurized liquid from the main dischargepassage 18, a hydraulic re-- lease needle valve I04 is provided. Thevalve'i04 is threaded into a valve chamber I05 whichopens into aco-axial passage I06 of smaller diameter than the valve chamber. A seatI01 for the needle valve I04 is provided at the offset between the valvechamber and the passage I06. The passage I06 opens into the verticalpass-age I02,

which in turn opens into the main discharge passage 18. From the needlevalve chamber I05 a horizontal passage I09 extends rearwardly and opensinto the reservoir I2. Thus, upon opening the release valve I04 fluid ispermitted to flow from the high pressure discharge passage 10 throughthe passages I08 and I00, through the valve chamber I05 and thencethrough the passage I09 back into the storage reservoir I2.

In describing the operation of the apparatus, let us assume that thedischarge passage 18 is connected to a, piece of hydraulic equipmentsuch as a hydraulic press, not shown. In the use of such presses it isusually desirable to have the ram thereof move some distance beforeencountering the main work load to be imposed on it.

The loads which may be handled, of course, will vary with changes in thesizes of the three cylinders 31, 08 and 44, and the relative length ofthe handle 28 and that of the lever arms through which the pistons areoperated. These values,- oi. course, can be calculated readily and it isbelieved to be unnecessary to set them forth for any specificapplication.

Assuming that the apparatus is ready to be operatedunder a progressivelyincreasing load, the adjusting plug 91 may be screwed in or out asdesired to an adjusted position substantially as indicated in Figs. 4and '7, so that the lower valve spring 99partly compensates for thebiasing action of the upper valve spring 92, but so that the reducedupper portion 93 of the stem Si is not in contact with the lower ballcheck 84. The cam 82 may be turned manually to move both of the camlobes 13 and 14 out of register with theball operating pins 15 or intoregistry with either one, or both of said pins as required. The reliefvalve I04 is closed. 7

The free end of the handle 28 then is moved reciprocally up and down tomove the lever 29,

a larger quantity of hydraulic fluid than the latter. The third cylinder44 not only is of larger diameter than either of the other two, but alsoit is pivoted at a greater distance from the fulcrum shaft 26, so thatit will have a longer stroke than the other two cylinders. It thereforehas a larger displacement than either of the other two cylinders.

Assuming for the purpose of illustration that the cam lobes 19 and 14are out of registry with their pins 15, initially all of the lower ballchecks 54 and 84 will be positioned on their seats. On an upward strokeof the operating handle 28 the free end of the lever 29 will rise,thereby raising all three pistons. This action, of course, reduces thepressure in the cylinders and permits the hydraulic liquid from thereservoir, under atmospheric pressure, to flow into all three cylindersthrough the intake passages previously described. On reaching the top ofthe handle stroke the atmospheric pressure from the reservoir isbalanced by the stopping of the pistons and the lower ball checks 54 and84 return to their seats by gravity.

On a downward stroke of the handle 28 the lever arm 29 forces the threepistons downwardly in their respective cylinders, therebyincreasing thepressure on the liquid in each. This increase inpressure is transmittedto'the passages between the upper and lower ball checks of eachcylinder, and tends to force the lower ball checks in each instance ontotheir seats and to raise the upper ball checks from their seats. Theupper ball checks will be raised from their seats as soon as thepressure below the ball checks increasesbeyond the pressure in thedischarge passages above them.

Since the passages I02, and I03 connect the discharge passage 18 to thevalve chamber 00 between the piston 89 and the plug 91, the dischargepressure thus is transmitted to the lowerflow of liquid back and forththrough the inlet passages past the open lower ball check 84.

As it is assumed, for the present illustration, that both the cam lobes13 and 14 are out of registry with their pins,15, continued operation ofthe handle after the largest cylinder 44 has thus been made inoperativewill be at a much greater mechanical advantage then before. The outputthen will be entirely by the two smaller cylinders 31 and 38', withtheir pistons operating through a shorter lever arm than the largestpiston.

If thereafter the load increases to a point where it is beyond thecapacity of both of the two smaller cylinders 31 and 38, either one orthe other of these two cylinders can be made inoperative by turning thecam handle 61 to bring either of the cam lobes 13 or 14 into engagementwith the pin 15 of the cylinder it isdesired to make inoperative. Thisraises the lower ball check 54 of the selected cylinder and preventsfurther pumping action by that cylinder. The upper ball check 55 of theinoperative cylinder holds the both inlet ball checks 56 from theirseats. When this is done, upon the pressure in the discharge passagerising sufiiciently to move the valve piston 89 upwardly to lift thelower ball check 86 from its seat, all three cylinders will thereupon beinoperative. The pressure will be held at this point until pumping iscontlnuedwith either the cylinder 3] or 38, or both, made operative byturning the cam handle 88 to move the cam lobe controlling the selectedcylinder out of contact with the pin controlling the ball check for thatcylinder.

After a working stroke of the operated mechanism has been completed, thepressure in the delivery zone can be released byturnlng the needle valveI (it to open it. Upon opening the needle valve, the pressurized liquidis free to flow from the main discharge passage 18 back into thereservoir i2,

While I have illustrated and described a preferred form of my invention,it will be clear to those familiar with the art that modifications canbe made without departing fromthe spirit of the invention. Therefore, itis not desired to limit the invention except as specifically defined inthe appended claims.

I claim:

L'A hydraulic apparatus comprising, in combination, a high pressurecylinder, a low pressure cylinder, common outlet means connected to bothcylinders, separate inlet means for each cylinder, a piston operativelymounted in each cylinder, a biased pressure operated valve operativelycontrolling the low pressure cylinder,

and a pressure transmitting connection between the common outlet and thepressure operated biased valve to transmit pressure from the commonoutlet to the valve in a direction opposed to the bias of the valve tomove the biased valve on the attainment of a predetermined pressure inthe common outlet to inactivate thev low pressure cylinder.

2. A hydraulic apparatus comprising, in combination, a high pressurecylinder, 9. low pressure cylinder, common outlet means connected toboth cylinders, separate inlet meansfor each cylinder, a pistonoperatively mounted in each cylinder, a

check valve operatively mounted between thecommon outlet and eachcylinder, a check valve operatively mounted in the inlet to eachcylinder, a biased pressure operated valve control member operativelycontrolling the inlet to the low pressure cylinder, and a pressuretransmitting connection between the common outlet and the pressureoperated biased valve to transmit pressure from the common outlet to thevalve in a direction opposed to the bias of the valve to move the biasedvalve on the attainment of a predetermined pressure in the common outletto inactivate the low pressure cylinder.

3. A hydraulic apparatus comprising, in combination, a high pressurecylinder, a low pressure cylinder, common outlet means connected to bothcylinders, separate inlet means for each cylinder, a piston operativelymounted in each cylinder, a checis valve operatively mounted between thecommon outlet and each cylindena check valve operatively mounted in theinlet to each cylinder, a biased pressure operated valve control membercomprising a cylindrical housing, a floating piston operatively mountedin the housing, spring biasing means mounted to act on one side of saidp ston, adjustable spring counterbalancing means mounted to operate onthe other side of said piston, and a pressure transmitting connectionbetween the common outlet and the pressure operated biased valve totransmit pressure from the common outlet to the valve in a directionopposed to the bias of the valve to move the biased valve on theattainment of a predetermined pressure in the common outlet toinactivate one of said cylinders.

4. A hydraulic apparatus comprising, in combination, a plurality of highpressure cylinders, a low pressure cylinder, common outlet meansconnected to both cylinders, separate inlet means for each cylinder, apiston operatively mounted in each cylinder, cam means selectivelycontrolling the inlet to each high pressure cylinder, a biased pressureoperated valve operatively controlling the inlet to the low pressurecylinder, and a pressure transmitting connection between the commonoutlet and the pressure operated biased valve to transmit pressure fromthe common outlet to the valve in a direction opposed to the bias of thevalve to move the biased valve on the attainment of a predeterminedpressure in the common outlet to inactivate one of said cylinders,

5. A hydraulic apparatus comprising, in combination, a cylinder blockhaving a fulcrumed handle, a high pressure cylinder and a low pressurecylinder in said cylinder block, a piston operatively mounted in eachcylinder, means operatively.

connecting the pistons to the fulcrumed handle, common outlet meansconnected to both cylinders, separate inlet means for each cylinder, acheck valve associated with each cylinder normally to prevent returnflow of liquid from the cylinder toward its inlet, a secondary checkvalve operatively mounted between each cylinder and a common outletnormally to prevent flow of liquid from the outlet toward the cylinder,a spring biased pressure actuated member associated with one of saidinlet valves, and a, pressure transmitting connection between the commonoutlet and the pressure operated biased member to transmit pressure fromthe common outlet to the biased member in a direction opposed to thebias of the I biased member to move the biased member relatively to oneof said inlet check valves on the attainment of a predetermined pressurein the common outlet to unseat said inlet check valve.

6. A hydraulic apparatus comprising, in combination, a cylinder blockhaving a plurality of cylinders formed therein, an operating handlefulcrumed on the cylinder block, a piston operatively mounted in eachcylinder, means operatively connecting the pistons to the handle, aliquid reservoir, a separate inlet passage from the reservoir into eachcylinder, an inlet check valve between each cylinder and the reservoir,a common outlet ior both cylinders, an outlet check valve betweenthecommon outlet and each cylinder, a biased valve control member normallyout of restrictive relation with the inlet check valves. pressureoperated means mounted to oppose the'bias of the valve control member.and pressure transmitting means operatively connecting the common outletand the pressure operated means, to operate the pressure operated meanson a predetermined increase in outlet pressure, thereby to move theseparate inlet passage from the reservoir into nected to the commonoutlet and to the side of each cylinder, an inlet check valve betweeneach cylinder and the reservoir, 9, common outlet for both cylinders, anoutlet check valve between the common outlet and each cylinder, a biasedvalve control member normally out of restrictive relation with the inletcheck valves, pressure operated means mounted to oppose the bias of thevalve control member, and pressure transmitting means operativelyconnecting the common outlet and the pressure operated means, to operatethe pressure operated means on a predetermined increase in outletpressure, thereby to move the biased valve control member into valveopening relation to one of the inlet check valves.

8. A hydraulic apparatus comprising in combination a cylinder block, ashaft pivoted on the block, an operating handle secured to the shaft, apiston actuating lever secured to the shaft, a pair of pivot pinscarried by the lever at diiferent distances from the shaft, a pair ofpistons operatively connected to the pivot pin which is closer to theshaft, a single larger piston operatively connected to the pivot pinwhich is farther from the shaft, a cylinder in the cylinder blockoperatively receiving each piston, a liquid reservoir, 8, separate inletpassage from the reservoir into each cylinder, an inlet check valvebetween each cylinder and the reservoir, a common outlet for bothcylinders, an outlet check valve between the common outlet and eachcylinder, a biased valve control member normally out of restrictiverelation with the inlet check valves, pressure operated means mounted tooppose the bias of the valve control member, and pressure transmittingmeans operatively connecting the common outlet and the pressure operatedmeans, to operate the pressure operated means on a predeterminedincrease in outlet pressure, thereby to move th biased valve controlmember into valve -opening relation to one of the inlet check valves.

9. A hydraulic apparatus comprising, in combination, a cylinder block, aplurality of cylinders formed in the cylinder block, an operating handlefulcrumed on the cylinder block, a piston operatively mounted in eachcylinder, means operatively connecting the pistons to the handle, aliquid reservoir, a separate inlet passage from the reservoir into eachcylinder, an inlet check valve between each cylinder and the reservoir,a common outlet for both cylinders, an outlet check valve between thecommon outlet and each cylinder, a cylindrical valve chamber formed inthe cylinder block, a floating piston mounted in the cylindrical valvechamber, a pin operatively connected to the piston and movable by thepiston into unseating engagement with the inlet check valve of one ofthe cylinders, a, spring mounted to exert a biasing force on the pistonaway from such unseating movement, a second spring mounted to exert aforce on the piston opposed to that, of the first spring, adjustingmeans mounted to adjust the relative forces of the two springs, andpressure transmittingmeans conthe piston opposed to'the biasing springto move the pin into unseating engagement with its check valve on apredetermined increase in pressure in the common outlet.-

10. A hydraulic apparatus comprising, in combination, a cylinder block,a plurality of cylinders formed in the cylinder block, an operatinghandle fulcrumed on the cylinder block, a piston operatively mounted ineach cylinder, means operatively connecting the pistons to the handle, a

liquid reservoir, a separate inlet passage from the reservoir into eachcylinder, an inlet check valve between each cylinder and the reservoir,9, common outlet for both cylinders, an outlet check valve between thecommon outlet and each cylinder, a cylindrical valve chamber formed inthe cylinder block, a floating piston mounted in the cylindrical valvechamber, a pin operatively connected to the piston and movable by thepiston into unseating engagement with the inlet check valve of one ofthe cylinders, a spring mounted to exert a biasing force on. the pistonaway from such unseating movement, a second spring mounted to exert aforce on the piston opposed to that of the first spring, adjusting meansmounted to adjust-the relative forces of the two springs, pressuretransmitting means connected to the common outlet and to the side of thepiston opposed to the biasing spring to move the pin into unseatingengagement with its check valve on. a predetermined increase in pressurein the common outlet, a pressure release passage from the common outletto the reservoir, and a pressure release valve mounted in the pressurerelease passage, said pressure release valve having a closed conditionto prevent flow of liquid from the common outlet to the reservoirthrough the passage, and an open condition to release liquid from thecommon outlet through the passage to the reservoir.

11. In a multi-stage pressure generator, a plurality of cylinders, afluid reservoir, valve controlled conduit means connecting the cylinderswith the reservoir and with an outlet, a piston operatively mounted ineach cylinder, lever means connectlng'the pistons to a common fulcrum,and pressure actuated release means operatively connected with one ofsaid cylinders to make ineffective the motion of the piston in said onecylinder on the attainment of a predetermined outlet cylinders to makeineifective the motion of the piston in said one cylinder on theattainment of a predetermined outlet pressure.

13. In a multi-stage pressure generator, a plurality of cylinders, afluid reservoir, valve controlled conduit means connecting the cylinderswith the reservoir and with an outlet, a piston mounted in eachcylinder, lever means of difierent lengths connecting the pistons to acommon fulcrum, and pressure actuated release means operativelyconnected to the cylinder having its piston operated by a longer of saidlever arms to make ineffective the motion of the piston in said lattercylinder on the attainment'of a predetermined outlet pressure.

V plurality of cylinders, a fluid reservoir, a common outlet from saidcylinders, ,a piston mounted in each cylinder, conduits connecting saidreservoir to said cylinders and other conduits connecting said cylindersto said outlet, inlet and outlet check valves associated with each saidcylinder respectively controlling flow into and out of said cylindersthrough said conduits in response 12 a to reciprocation oi'said pistons,means for reciprocating said pistons, pressure actuated means -formoving the inlet check valve associated with one of said cylinders toopen position, means ren-i dering said pressure actuated meansresponsive to the fluid pressure at said outlet, and means inhibitingactuation of said pressure actuated means until a fluid pressure of pnin value is attained at said outlet.

HERBERT E. PAGE.

REFERENCES I The following references are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 753,530 Ten Eyck Mar. 1, 19041,781,404 McNab Nov, 11, 1930 so 1,829,451 McNab Oct. 27, 1931 McGeeJune 15, 1937

